In class, I often work with students to remember that there is a difference between the way we speak and write and the way we do so at home. This seems to lessen a "critical" impact. I even use myself as an example. I have a strong Southern twang/drawl when I am around family and friends, but in the workplace (classroom) I use standard English. I have also used Spanish when tutoring students as a lead in to English, getting them to understand the concepts first in Spanish, then leading them to explain the same concepts to me back in English. It reinforces the conceptual learning and English skills.